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| Titel |
Lichen-moss interactions within biological soil crusts |
| VerfasserIn |
Nina Ruckteschler, Laura Williams, Burkhard Büdel, Bettina Weber |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250110167
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| Publikation (Nr.) |
 EGU/EGU2015-10141.pdf |
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| Zusammenfassung |
| Biological soil crusts (biocrusts) create well-known hotspots of microbial activity, being
important components of hot and cold arid terrestrial regions. They colonize the
uppermost millimeters of the soil, being composed of fungi, (cyano-) bacteria,
algae, lichens, bryophytes and archaea in varying proportions. Biocrusts protect the
(semi-) arid landscape from wind and water erosion, and also increase water holding
capacity and nutrient content. Depending on location and developmental stage,
composition and species abundance vary within biocrusts. As species live in close
contact, they are expected to influence each other, but only a few interactions between
different organisms have so far been explored. In the present study, we investigated the
effects of the lichen Fulgensia fulgens whilst growing on the moss Trichostomum
crispulum.
While 77% of Fulgensia fulgens thalli were found growing associated with mosses in a
German biocrust, up to 95% of Fulgensia bracteata thalli were moss-associated in a Swedish
biocrust. In 49% (Germany) and in 78% (Sweden) of cases, thalli were observed on the moss
T. crispulum and less frequently on four and three different moss species. Beneath F. fulgens
and F. bracteata thalli, the mosses were dead and in close vicinity to the lichens the
mosses appeared frail, bringing us to the assumption that the lichens may release
substances harming the moss. We prepared a water extract from the lichen F. fulgens and
used this to water the moss thalli (n = 6) on a daily basis over a time-span of three
weeks. In a control setup, artificial rainwater was applied to the moss thalli (n = 6).
Once a week, maximum CO2 gas exchange rates of the thalli were measured under
constant conditions and at the end of the experiment the chlorophyll content of the
moss samples was determined. In the course of the experiment net photosynthesis
(NP) of the treatment samples decreased concurrently with an increase in dark
respiration (DR). The control samples remained at the same stable level for both NP and
DR over time. The chlorophyll content of the treatment samples was significantly
lower than that of the controls. This supports our assumption that water extracts
of F. fulgens may indeed cause a dieback of the host moss. In a next step of the
project, the substances responsible for this detrimental effect on the moss will be
identified.
The accelerated dieback of the moss probably causes increased CO2 concentrations below
the lichen thalli, improving their overall photosynthetic performance. Thus, both dead and
living biomass in biocrusts increase upon this association, promoting microbial activity and
the growth of vascular plant vegetation. |
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